mbuf: expand ol_flags field to 64-bits

mbuf: expand ol_flags field to 64-bits

The offload flags field (ol_flags) was 16-bits and had no further room
for expansion. This patch increases the field size to 64-bits, using up
the remaining reserved space in the single-cache-line mbuf.

NOTE: none of the values for existing flags have been changed, i.e. no
new numbers have been explicitly reserved between existing flag
definitions.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>